xletters - catch falling words
xletters [ options ]
X Letters is a game under X to improve your typing skill. It is
inspired by the game letters(6) by Larry Moss and Brent Nordquist
(which itself is inspired by the game Letter Invaders, and ultimately
by the famous Space Invaders).
The goal of the game is to destroy the words that fall down from the
top before they reach the bottom. To destroy a word, you must simply
The game is organized in levels of increasing difficulty. Each level
is divided into two parts: a normal part and a bonus part. During the
normal part, ordinary english words will fall down (found in the
system’s dictionary, usually /usr/dict/words). During the bonus part,
the words are randomly generated from printable ascii characters.
If a word hits the ground during the normal part, you lose a life (you
have five lives initially), and the word disappears (but the others
keep on falling). If a word hits the ground during the bonus part, the
bonus part simply ends, with no additional penalty, and the game
proceeds to the next level.
The normal part of a level ends when a certain time has elapsed. The
bonus part ends when either a certain time has elapsed or when a word
has hit the ground. The normal duration of a half-level is 600 time
units, or 45 seconds (whatever the level).
Typing a word correctly makes the word disappear and scores you one
point per letter, plus five more points, plus another extra three
points if the word was destroyed in the top fifth of the window. This
is the only way of gaining points: partially typed words are not worth
anything, and even moving to another level doesn’t bring you points
(this is because even if you don’t type anything you will go beyond the
Short words fall faster than long ones. Unless otherwise specified at
compile time, words are not allowed to collide into one another.
Therefore, when a new word appears, the game makes sure that all the
words below it fall at least as fast as it. The fall rate of the words
also increases with the level (it is, however, the same between the
normal part and the bonus part of the same level). The rate at which
words appear is constant on a given level, but it increases with the
A word is considered typed when the last printable characters that you
typed since the word appeared are precisely the letters of the word.
This means in particular that it is possible to ‘‘kill two birds with
one stone’’ if one word ends with the letters with which another one
begins - in fact, if two identical words appear (an unlikely but not
impossible situation), you need only type one of them. To say things
differently, if you type a correct letter it will make your position in
the word advance by one letter, and if you type an incorrect letter, it
will make your position move back to the last place in the word that
matches the characters you typed. The current position in each word is
indicated by putting the already typed letters in a different color
(normally red). Note that a different behaviour is selectable at
compile time with which a wrong letter will cause all letters to be
considered wrong (to make the difference obvious, consider the word
‘‘abracadabrx’’: if after having typed ‘‘abracadabr’’ you press an
‘‘a’’, the normal behaviour will take you back to ‘‘abra’’ whereas the
alternate behaviour will take you back to the beginning).
The game keeps a high score table. When the game is over, one way or
another, xletters will show, for the user and for the twenty best
players, the name, the level reached, the final score, and the time
during which the game was running. Normally, each player is allowed
only one entry in the high score table. This can be modified at
compilation time, however.
The top of the window shows three buttons. The Quit button will take
you out of the game, the Pause button will pause the game or resume it
if it was already paused, and the Next button will move to the next
level (normal part). These buttons can also be accessed through
accelerators: the ‘‘Escape’’ key will quit the game, the ‘‘Tab’’ key
(or ‘‘Pause’’ if you have one) will suspend it or resume it, and the
‘‘Page Down’’ key (or ‘‘Next’’ if it is so labeled) will advance one
Three labels on the right of the buttons are used to indicate your
lives, score and current level.
Other than that, to play the game you must simply type the words. In
order for the typing to be effective, your mouse cursor must be in the
game space (the large square area below the buttons and labels). If
you start typing while the game is paused, it will automatically
Scoring is made much more complicated if you choose to use the Next
button to warp through levels. (The point is that it should be used to
avoid having to go through all the easy levels if you already type very
fast. So it should not handicap you excessively by giving you no
points which you would have gotten if you had worked your way through
those levels. On the other hand, it should not be an obvious way of
gaining arbitrarily many points.) Here is the way it works: when you
use the Next button to warp to the next level, you gain 350 ‘‘virtual’’
points. Those points are indicated in parentheses after your real
points in the score label. They are not worth anything by themselves.
On the other hand, if you have virtual points, every time you gain some
points, that many virtual points will also be converted to real points
(until you no longer have virtual points). Thus, virtual points are
worth something only if you prove yourself good enough to make them so.
There are some restrictions to the use of the Next button. First, it
will only work in the bonus part of a level, or if no word has fallen
lower than the top fifth of the screen. This is so you can’t use it to
get yourself easily out of a tricky situation. Second, if you already
scored some points on the current level, using the Next button will
award you fewer than the normal 350 virtual points (see above), in fact
precisely twice fewer than as many points as you gained on the level
(but no less than zero, of course).
xletters has a training mode, which you can invoke using the -train
command line option. In training mode, only one (english) word appears
at a time, anywhere on the game space, and it does not fall. A new
word appears as soon as you finish typing the previous one. In
training mode, there are no lives, points, levels, or bonus words.
DEATHMATCH AND DUEL
xletters also has the amazing ‘‘deathmatch’’ mode. To invoke this
mode, use the -death command line option. This has the following
effects on the behaviour of xletters: first, it will read words on the
standard input, and make them fall. Second, you can choose between
typing falling words, or typing a special word in a special part of the
display, just above the game space. To switch between both modes, use
the Mode button or press the ‘‘Backspace’’ key. The special word typed
must be an english word: if the letter you type makes the word fragment
no longer begin a word in the dictionary, it immediately disappears.
When you type a full word, you can then send it by using the Send
button or by pressing the ‘‘Return’’ key. The word sent gets printed
on the standard output.
These features make sense when two copies of xletters are run in
deathmatch mode, with the standard output of each being sent to the
standard input of the other (possibly across the network). Then the
player on each game can not only kill his falling words but also send
words to the other player.
Even more extreme than the ‘‘deathmatch’’ mode is the ‘‘duel’’ mode,
activated through the -duel command switch. In duel mode, the computer
does not send words of its own, and only words sent through the
standard input will appear. In this case, there is no Next button, and
switching to the next level can only occur after a certain amount of
time. In fact, there are no bonus parts of levels, so levels change
twice more rapidly than in normal play. Moreover, a level change does
not erase all the current words contrary to what happens in normal (or
The X Letters distribution includes a shell script named xletters-duel
which uses Avian Research’s netcat program (nc) to open a socket, run
xletters in duel mode, and try to connect to the same socket on a given
computer. Thus, two people on two different computers can play a duel
by each running xletters-duel with the name of the other’s computer as
parameter. (Both copies must be run within five seconds of the other.)
X Letters recognizes all the standard X Toolkit command line options,
among which the following:
Specifies the background color to use.
Specifies the foreground color to use for the labels and
Specifies the font to use for displaying the labels and buttons.
Specifies the application name under which resources are to be
obtained, rather than under the default executable file name.
name should not contain ‘‘.’’ or ‘‘*’’ characters.
Specifies the window title string.
Specifies the preferred position of the window. Specifying a
size is not recommended.
Specifies the X server to use.
Explicitely give a resource string.
The following additional options are recognized by xletters:
Specifies the font to use for the falling words. (Sets the
Specifies which color to use for the words. (Sets the wordColor
Specifies which color to use for the correctly typed part of the
words. (Sets the typedColor resource.)
Specifies which color to use for the background of the game
space. (Sets the gameSpace.background resource.)
Do not go in training mode (this is the default). (Sets the
trainingMode resource to ‘‘False’’.)
-train Run the game in training mode (see TRAINING MODE above). (Sets
the trainingMode resource to ‘‘True’’.)
Do not run in deathmatch or duel mode (this is the default).
(Sets the deathMode resource to ‘‘normal’’.)
-death Run in deathmatch mode (see DEATHMATCH AND DUEL above). (Sets
the deathMode resource to ‘‘death’’.)
-duel Run in duel mode (see DEATHMATCH AND DUEL above). (Sets the
deathMode resource to ‘‘duel’’.)
In addition, xletters recognizes -help and -version options.
groundBox (class Box, parent (toplevel))
This is the main application box that supports all the other
label (class Label, parent groundBox)
The xletters label. The text of this label cannot be changed.
quitButton (class Command, parent groundBox)
The Quit button.
pauseButton (class Toggle, parent groundBox)
The Pause button.
livesLabel (class Label, parent groundBox)
The lives label.
scoreLabel (class Label, parent groundBox)
The score label.
levelLabel (class Label, parent groundBox)
The level label.
gameSpace (class Core, parent groundBox)
The game space in which the words fall. Key presses and Expose
events are handled through event handlers and not the ordinary
In addition to the resources of the various widgets, the xletters
application itself recognizes some resources. These are:
wordFont (class Font, type FontStruct)
The font in which the falling words are written.
wordColor (class Foreground, type Pixel)
The color in which the (untyped part of the) falling words are
typedColor (class HighlightColor, type Pixel)
The color in which the typed part of the falling words are
deathMode (class DeathMode, type String)
Either normal, death or duel according as the game should be run
in normal, deathmatch or duel mode (see DEATHMATCH AND DUEL
trainingMode (class TrainingMode, type Boolean)
Whether the game should be run in training mode (this overrides
any value of the deathMode resource (see TRAINING MODE above).
(If not overriden at compile time)
The dictionary of words.
The high score table.
’MidnightBlue’ -wc ’PaleGoldenrod’ -tc ’Orchid’
None known. Surely a very temporary situation :-)
This is one of the ugliest programs I ever wrote. I would not be
surprized to discover plenty of bugs in it. Version 1.0.0 was ugly
enough. Version 1.1.0 gave a whole new meaning to the word
xletters wants to access a high score table. If this score table is to
be shared between several users, xletters will probably be made sgid
games or some such thing. Beware that it is probably very easy to fool
(or even brake to pieces). I have no doubt that running it against a
fake X server (and probably other similar things) can give not-too-hard
access to whatever permissions it has been given. Consequently, it
should not be given any critical permissions.
Peter Horvai (email@example.com) wrote the deathmatch feature and
implemented mmap()ing the dictionary file.
David Madore (firstname.lastname@example.org) wrote version 1.0.0, all the X
Windows parts of the game, and this man page.
GNU public license. See the file COPYING for more information.
05 NOV 1998